            (j/offset-date-time (j/instant clock) "UTC")))
 
     (is (= (j/truncate-to (j/offset-date-time clock) :millis)
-          (j/offset-date-time (j/to-java-date clock) "UTC")))
+           (j/offset-date-time (j/to-java-date clock) "UTC")))
 
     (is (j/offset-date-time? (j/offset-date-time)))
+    (is (not (j/offset-date-time? nil)))
 
     (j/with-clock (j/system-clock "UTC")
       (is (= (j/offset-date-time 2015)

           (j/offset-time (j/instant clock) "UTC")))

    (is (= (j/truncate-to (j/offset-time clock) :millis)
          (j/offset-time (j/to-java-date clock) "UTC")))

    (is (j/offset-time? (j/offset-time (j/zone-id "UTC"))))
    (is (j/offset-time? (j/offset-time +0)))


    (testing "number ops"
      (is (j/zero? (j/duration 0)))
      (is (not (j/zero? (j/duration 10))))
      (is (= (j/duration 10) (j/abs (j/duration -10))))
      (is (= (j/duration -10) (j/negate (j/duration 10))))
      (is (= (j/duration 10) (j/min (j/duration 10) (j/duration 11) (j/duration 12))))
      (is (= (j/duration 12) (j/max (j/duration 10) (j/duration 11) (j/duration 12))))
      (is (j/negative? (j/duration -10)))
      (is (not (j/negative? (j/duration 10))))))

  (testing "period"
    (testing "plus"
